1EC_POINT_NEW(3ossl)                 OpenSSL                EC_POINT_NEW(3ossl)
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NAME

6       EC_POINT_set_Jprojective_coordinates_GFp, EC_POINT_point2buf,
7       EC_POINT_new, EC_POINT_free, EC_POINT_clear_free, EC_POINT_copy,
8       EC_POINT_dup, EC_POINT_method_of, EC_POINT_set_to_infinity,
9       EC_POINT_get_Jprojective_coordinates_GFp,
10       EC_POINT_set_affine_coordinates, EC_POINT_get_affine_coordinates,
11       EC_POINT_set_compressed_coordinates,
12       EC_POINT_set_affine_coordinates_GFp,
13       EC_POINT_get_affine_coordinates_GFp,
14       EC_POINT_set_compressed_coordinates_GFp,
15       EC_POINT_set_affine_coordinates_GF2m,
16       EC_POINT_get_affine_coordinates_GF2m,
17       EC_POINT_set_compressed_coordinates_GF2m, EC_POINT_point2oct,
18       EC_POINT_oct2point, EC_POINT_point2bn, EC_POINT_bn2point,
19       EC_POINT_point2hex, EC_POINT_hex2point - Functions for creating,
20       destroying and manipulating EC_POINT objects
21

SYNOPSIS

23        #include <openssl/ec.h>
24
25        EC_POINT *EC_POINT_new(const EC_GROUP *group);
26        void EC_POINT_free(EC_POINT *point);
27        void EC_POINT_clear_free(EC_POINT *point);
28        int EC_POINT_copy(EC_POINT *dst, const EC_POINT *src);
29        EC_POINT *EC_POINT_dup(const EC_POINT *src, const EC_GROUP *group);
30        int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point);
31        int EC_POINT_set_affine_coordinates(const EC_GROUP *group, EC_POINT *p,
32                                            const BIGNUM *x, const BIGNUM *y,
33                                            BN_CTX *ctx);
34        int EC_POINT_get_affine_coordinates(const EC_GROUP *group, const EC_POINT *p,
35                                            BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
36        int EC_POINT_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *p,
37                                                const BIGNUM *x, int y_bit,
38                                                BN_CTX *ctx);
39        size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *p,
40                                  point_conversion_form_t form,
41                                  unsigned char *buf, size_t len, BN_CTX *ctx);
42        size_t EC_POINT_point2buf(const EC_GROUP *group, const EC_POINT *point,
43                                  point_conversion_form_t form,
44                                  unsigned char **pbuf, BN_CTX *ctx);
45        int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *p,
46                               const unsigned char *buf, size_t len, BN_CTX *ctx);
47        char *EC_POINT_point2hex(const EC_GROUP *group, const EC_POINT *p,
48                                 point_conversion_form_t form, BN_CTX *ctx);
49        EC_POINT *EC_POINT_hex2point(const EC_GROUP *group, const char *hex,
50                                     EC_POINT *p, BN_CTX *ctx);
51
52       The following functions have been deprecated since OpenSSL 3.0, and can
53       be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
54       version value, see openssl_user_macros(7):
55
56        const EC_METHOD *EC_POINT_method_of(const EC_POINT *point);
57        int EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group,
58                                                     EC_POINT *p,
59                                                     const BIGNUM *x, const BIGNUM *y,
60                                                     const BIGNUM *z, BN_CTX *ctx);
61        int EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
62                                                     const EC_POINT *p,
63                                                     BIGNUM *x, BIGNUM *y, BIGNUM *z,
64                                                     BN_CTX *ctx);
65        int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
66                                                const BIGNUM *x, const BIGNUM *y,
67                                                BN_CTX *ctx);
68        int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group,
69                                                const EC_POINT *p,
70                                                BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
71        int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
72                                                    EC_POINT *p,
73                                                    const BIGNUM *x, int y_bit,
74                                                    BN_CTX *ctx);
75        int EC_POINT_set_affine_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
76                                                 const BIGNUM *x, const BIGNUM *y,
77                                                 BN_CTX *ctx);
78        int EC_POINT_get_affine_coordinates_GF2m(const EC_GROUP *group,
79                                                 const EC_POINT *p,
80                                                 BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
81        int EC_POINT_set_compressed_coordinates_GF2m(const EC_GROUP *group,
82                                                     EC_POINT *p,
83                                                     const BIGNUM *x, int y_bit,
84                                                     BN_CTX *ctx);
85        BIGNUM *EC_POINT_point2bn(const EC_GROUP *group, const EC_POINT *p,
86                                  point_conversion_form_t form, BIGNUM *bn,
87                                  BN_CTX *ctx);
88        EC_POINT *EC_POINT_bn2point(const EC_GROUP *group, const BIGNUM *bn,
89                                    EC_POINT *p, BN_CTX *ctx);
90

DESCRIPTION

92       An EC_POINT structure represents a point on a curve. A new point is
93       constructed by calling the function EC_POINT_new() and providing the
94       group object that the point relates to.
95
96       EC_POINT_free() frees the memory associated with the EC_POINT.  if
97       point is NULL nothing is done.
98
99       EC_POINT_clear_free() destroys any sensitive data held within the
100       EC_POINT and then frees its memory. If point is NULL nothing is done.
101
102       EC_POINT_copy() copies the point src into dst. Both src and dst must
103       use the same EC_METHOD.
104
105       EC_POINT_dup() creates a new EC_POINT object and copies the content
106       from src to the newly created EC_POINT object.
107
108       EC_POINT_method_of() obtains the EC_METHOD associated with point.  This
109       function was deprecated in OpenSSL 3.0, since EC_METHOD is no longer a
110       public concept.
111
112       A valid point on a curve is the special point at infinity. A point is
113       set to be at infinity by calling EC_POINT_set_to_infinity().
114
115       The affine co-ordinates for a point describe a point in terms of its x
116       and y position. The function EC_POINT_set_affine_coordinates() sets the
117       x and y co-ordinates for the point p defined over the curve given in
118       group. The function EC_POINT_get_affine_coordinates() sets x and y,
119       either of which may be NULL, to the corresponding coordinates of p.
120
121       The functions EC_POINT_set_affine_coordinates_GFp() and
122       EC_POINT_set_affine_coordinates_GF2m() are synonyms for
123       EC_POINT_set_affine_coordinates(). They are defined for backwards
124       compatibility only and should not be used.
125
126       The functions EC_POINT_get_affine_coordinates_GFp() and
127       EC_POINT_get_affine_coordinates_GF2m() are synonyms for
128       EC_POINT_get_affine_coordinates(). They are defined for backwards
129       compatibility only and should not be used.
130
131       As well as the affine co-ordinates, a point can alternatively be
132       described in terms of its Jacobian projective co-ordinates (for Fp
133       curves only). Jacobian projective co-ordinates are expressed as three
134       values x, y and z. Working in this co-ordinate system provides more
135       efficient point multiplication operations.  A mapping exists between
136       Jacobian projective co-ordinates and affine co-ordinates. A Jacobian
137       projective co-ordinate (x, y, z) can be written as an affine co-
138       ordinate as (x/(z^2), y/(z^3)). Conversion to Jacobian projective from
139       affine co-ordinates is simple. The co-ordinate (x, y) is mapped to (x,
140       y, 1). Although deprecated in OpenSSL 3.0 and should no longer be used,
141       to set or get the projective co-ordinates in older versions use
142       EC_POINT_set_Jprojective_coordinates_GFp() and
143       EC_POINT_get_Jprojective_coordinates_GFp() respectively.  Modern
144       versions should instead use EC_POINT_set_affine_coordinates() and
145       EC_POINT_get_affine_coordinates(), performing the conversion manually
146       using the above maps in such rare circumstances.
147
148       Points can also be described in terms of their compressed co-ordinates.
149       For a point (x, y), for any given value for x such that the point is on
150       the curve there will only ever be two possible values for y. Therefore,
151       a point can be set using the EC_POINT_set_compressed_coordinates()
152       function where x is the x co-ordinate and y_bit is a value 0 or 1 to
153       identify which of the two possible values for y should be used.
154
155       The functions EC_POINT_set_compressed_coordinates_GFp() and
156       EC_POINT_set_compressed_coordinates_GF2m() are synonyms for
157       EC_POINT_set_compressed_coordinates(). They are defined for backwards
158       compatibility only and should not be used.
159
160       In addition EC_POINT can be converted to and from various external
161       representations. The octet form is the binary encoding of the ECPoint
162       structure (as defined in RFC5480 and used in certificates and TLS
163       records): only the content octets are present, the OCTET STRING tag and
164       length are not included. BIGNUM form is the octet form interpreted as a
165       big endian integer converted to a BIGNUM structure. Hexadecimal form is
166       the octet form converted to a NULL terminated character string where
167       each character is one of the printable values 0-9 or A-F (or a-f).
168
169       The functions EC_POINT_point2oct(), EC_POINT_oct2point(),
170       EC_POINT_point2bn(), EC_POINT_bn2point(), EC_POINT_point2hex() and
171       EC_POINT_hex2point() convert from and to EC_POINTs for the formats:
172       octet, BIGNUM and hexadecimal respectively.
173
174       The function EC_POINT_point2oct() encodes the given curve point p as an
175       octet string into the buffer buf of size len, using the specified
176       conversion form form.  The encoding conforms with Sec. 2.3.3 of the
177       SECG SEC 1 ("Elliptic Curve Cryptography") standard.  Similarly the
178       function EC_POINT_oct2point() decodes a curve point into p from the
179       octet string contained in the given buffer buf of size len, conforming
180       to Sec. 2.3.4 of the SECG SEC 1 ("Elliptic Curve Cryptography")
181       standard.
182
183       The functions EC_POINT_point2hex() and EC_POINT_point2bn() convert a
184       point p, respectively, to the hexadecimal or BIGNUM representation of
185       the same encoding of the function EC_POINT_point2oct().  Vice versa,
186       similarly to the function EC_POINT_oct2point(), the functions
187       EC_POINT_hex2point() and EC_POINT_point2bn() decode the hexadecimal or
188       BIGNUM representation into the EC_POINT p.
189
190       Notice that, according to the standard, the octet string encoding of
191       the point at infinity for a given curve is fixed to a single octet of
192       value zero and that, vice versa, a single octet of size zero is decoded
193       as the point at infinity.
194
195       The function EC_POINT_point2oct() must be supplied with a buffer long
196       enough to store the octet form. The return value provides the number of
197       octets stored.  Calling the function with a NULL buffer will not
198       perform the conversion but will still return the required buffer
199       length.
200
201       The function EC_POINT_point2buf() allocates a buffer of suitable length
202       and writes an EC_POINT to it in octet format. The allocated buffer is
203       written to *pbuf and its length is returned. The caller must free up
204       the allocated buffer with a call to OPENSSL_free(). Since the allocated
205       buffer value is written to *pbuf the pbuf parameter MUST NOT be NULL.
206
207       The function EC_POINT_point2hex() will allocate sufficient memory to
208       store the hexadecimal string. It is the caller's responsibility to free
209       this memory with a subsequent call to OPENSSL_free().
210

RETURN VALUES

212       EC_POINT_new() and EC_POINT_dup() return the newly allocated EC_POINT
213       or NULL on error.
214
215       The following functions return 1 on success or 0 on error:
216       EC_POINT_copy(), EC_POINT_set_to_infinity(),
217       EC_POINT_set_Jprojective_coordinates_GFp(),
218       EC_POINT_get_Jprojective_coordinates_GFp(),
219       EC_POINT_set_affine_coordinates_GFp(),
220       EC_POINT_get_affine_coordinates_GFp(),
221       EC_POINT_set_compressed_coordinates_GFp(),
222       EC_POINT_set_affine_coordinates_GF2m(),
223       EC_POINT_get_affine_coordinates_GF2m(),
224       EC_POINT_set_compressed_coordinates_GF2m() and EC_POINT_oct2point().
225
226       EC_POINT_method_of returns the EC_METHOD associated with the supplied
227       EC_POINT.
228
229       EC_POINT_point2oct() and EC_POINT_point2buf() return the length of the
230       required buffer or 0 on error.
231
232       EC_POINT_point2bn() returns the pointer to the BIGNUM supplied, or NULL
233       on error.
234
235       EC_POINT_bn2point() returns the pointer to the EC_POINT supplied, or
236       NULL on error.
237
238       EC_POINT_point2hex() returns a pointer to the hex string, or NULL on
239       error.
240
241       EC_POINT_hex2point() returns the pointer to the EC_POINT supplied, or
242       NULL on error.
243

SEE ALSO

245       crypto(7), EC_GROUP_new(3), EC_GROUP_copy(3), EC_POINT_add(3),
246       EC_KEY_new(3), EC_GFp_simple_method(3), d2i_ECPKParameters(3)
247

HISTORY

249       EC_POINT_method_of(), EC_POINT_set_Jprojective_coordinates_GFp(),
250       EC_POINT_get_Jprojective_coordinates_GFp(),
251       EC_POINT_set_affine_coordinates_GFp(),
252       EC_POINT_get_affine_coordinates_GFp(),
253       EC_POINT_set_compressed_coordinates_GFp(),
254       EC_POINT_set_affine_coordinates_GF2m(),
255       EC_POINT_get_affine_coordinates_GF2m(),
256       EC_POINT_set_compressed_coordinates_GF2m(), EC_POINT_point2bn(), and
257       EC_POINT_bn2point() were deprecated in OpenSSL 3.0.
258
259       EC_POINT_set_affine_coordinates, EC_POINT_get_affine_coordinates, and
260       EC_POINT_set_compressed_coordinates were added in OpenSSL 1.1.1.
261
263       Copyright 2013-2021 The OpenSSL Project Authors. All Rights Reserved.
264
265       Licensed under the Apache License 2.0 (the "License").  You may not use
266       this file except in compliance with the License.  You can obtain a copy
267       in the file LICENSE in the source distribution or at
268       <https://www.openssl.org/source/license.html>.
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2723.0.5                             2022-11-01               EC_POINT_NEW(3ossl)
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